Lithographic developer containing an anionic fatty alcohol sulfate and a nonionic polyethylene oxide surfactant

ABSTRACT

An aqueous photolithographic developer comprising a hydroquinone or a substituted hydroquinone developing agent, an anionic fatty alcohol sulfate and a nonionic polyethylene oxide surfactant in combination with conventional developer adjuvants, e.g., antifoggants, buffers, preservatives, etc.

United States Patent 1 1 3,622,330

[72] inventor George Devasla Valilveedan [56] References Cited Fmhdd Tw'lshllh UNITED STATES'PATENTS 2,531,832 11/1950 Stanton 96/66 [22] F1led Dec. 19, 1969 3,158,483 11/1964 Lowe et a1. 96/663 [45] 3 272 628 9/1966 Connoll etal 96/66 [73] Assignee E. l. du Pontde Nemoulsand Company y Wilmington, Del. Primary Examiner-Norman G. Torchin Assistant Examiner-Mary F. Kelley Attorney-Lynn Barratt Morris 54] LITHOGRAPHIC DEVELOPER CONTAINING AN ANION lC FA'l'lY ALCOHOL SULFATE AND A NONIONIC POLYETHYLENE OXIDE ABSTRACT: An aqueous photolithographic developer com- SURFACTANT prising a hydroquinone or a substituted hydroquinone 7 Claim ,No Drawing developing agent, an anionic fatty alcohol sulfate and a nonionic polyethylene oxide surfactant in combination with [52] US. Cl conventional developer adj-Wants elgq antifoggams buffers 511 1m. 01 G03 5/30 prese'vatives' [50] Field of Search 96/66, 66.3,

LITI-IOGRAPIIIC DEVELOPER CONTAINING AN ANIONIC FATTY ALCOHOL SULFATE AND A NONIONIC POLYETIIYLENE OXIDE SURFACTANT BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photolithographic processing. More particularly, it relates to improved silver halide developers having surfactants therein which produce superior dot quality.

2. Description of the Prior Art Various developer additives are known and employed in the field of photographic processing to produce clearly defined, high-contrast images. The practice is particularly well known in the graphic arts industry. In order to produce the desired halftone "dot quality" and sharp image formation, it is necessary that a suitable developer be used with an appropriate photosensitive material. Emulsion parameters, aside from developer composition, play an important role.

Many modifications in both the photosensitive material and the processing solutions have been designed to remedy the problems encountered in lithographic processing.

A. Schaeffer, US. Pat. No. 2,000,353, teaches a method of introducing the photographic material to a bath containing organic wetting agents such as sodium benzylnaphthalene sulfonate prior to development. Addition of certain surfactants to the developer has proven most effective in facilitating good dot quality" and image sharpness. Surfactants may be added to the emulsion or separated between the same and the developer to improve coating quality. Levy, US. Pat. No. 3,238,043, describes a separation system using a viscous developing solution of materials such as sodium polyacrylate and sodium heptadecyl sulfate and water-soluble, high molecular weight polymers of ethylene oxide. Use of polyethylene glycols in silver halide developer to reduce the induction period is taught by W. A. Stanton, US. Pat. No. 2,53 l ,832. Also use of polyalkylene glycols or alkylene oxide polymers in a hydroquinone or substituted hydroquinone developer having low ionized sulfite to produce good dot quality" is described in G. Lowe et al., US. Pat. No. 3,l58,483.

Said dot quality," as discussed in Nottorf, U.S. Pat. No. 3, l 42,568, is the production of halftone dots having high density and well defined image sharpness. In such a system the processed samples are evaluated through microscopic observations and rated subjectively on a numerical scale from I to 4 ofdiminishing quality wherein 1.0 is excellent and 4.0 is unacceptably poor.

Many compositions like those discussed above and various similar conventional formulations have proven adequate as conventional developers and have been accepted commercially as such. However, laboratory experiments have shown that particular surfactant combinations provide more efficient development mechanisms. Unlike the aforementioned prior art, the present invention involves a processing system wherein the cofunctioning surfactants have been eliminated from the emulsion and placed in the developer. And it is in accordance with the basic kinetics of this process that the instant invention discloses a system which will facilitate production of superior halftone dot quality, increase speed, and eliminate any undesirable discoloration.

SUMMARY OF THE INVENTION An aqueous hydroquinone or substituted hydroquinone developer comprising, per liter of working strength solution, 0.2 4.0 grams of an anionic alkyl sulfate having between eight and carbon atoms in combination with 0.25 and 5.0 grams of a nonionic polyethylene oxide surfactant having at least two ethylene oxide groups. Said anionic and nonionic combination which may be admixed with various conventional lithographic developers is capable of rendering the same more efficient.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The new developers which are employed in accordance with this invention are members of the lithographic developer family. More specifically the developers described herein are of the hydroquinone or substituted hydroquinone classes having high pH and certain surfactants added to appreciably affect film characteristics such as speed, dot quality, and image color. Said surfactants, 0.2 to 4.0 grams of an anionic alkyl sulfate and 0.25 to 5.0 grams of a nonionic polyethylene oxide surfactant per liter of working strength solution cofunction in the development process.

The anionic alkyl sulfate has the general formula, ROSO M is a suitably soluble, alkali metal such as potassium, lithium or preferably sodium, wherein, R, the alkyl group, may be a saturated or unsaturated straight or branched chain. Said alkyl groups may be from eight to 20 carbon atoms. Saturated compounds such as sodium dodecyl (lauryl), tridecyl, tetradecyl sulfates through and include sodium eicosyl sulfate fall into this category. Those sodium or potassium alkyl sulfates having an unsaturated aliphatic chain would include compounds such as sodium and potassium oleyl sulfate.

Development additives of the polyethylene oxide class disclosed herein would include those compounds having the general formula RO(CH Cl-I O),,CH CH OH where n may be 2 or more, R represents an alkyl, aryl or substituted aryl group, and Cl-I Cl-I O is the functional group. Said alkyl groups may or may not be saturated or substituted. The polyethylene oxide surface active compounds of the type described herein include the condensation products formed by reaction of ethylene oxide with alcohol, soluble phenols, alkyl phenols, carboxylic acids, amines, amides and also urethanes formed from polyethylene oxides or glycol. Condensation products of ethylene oxide with long chain carboxylic acids, R-CO-(OC- l-I,),,OH, where R-CO is an acyl radical of a fatty acid such as lauric, palmitic, oleic, stearic, etc. and n is 2 to 450 are useful.

Preferred developer concentrations in grams per liter of working strength solution are as follows:

Alkali metal alkyl sulfate 0.2-4

Nnnionic polyethylene oxide surfactant 0.25-5

Developing Agent 5-75 Auxiliary Solvents 20-l00 Caustic Alkali Hardeners or Hardener Adducts 5-80 Preservatives or Antioxidants Restrainers l- Buffering Agents 2()IOO sequestering Agents 0.54

Water to make I liter This invention will be further illustrated by, but is not intended to be limited to, the following examples wherein commercially available films were processed in standard and various preferred developers and compared for developability.

EXAMPLES I-XVII A sufficient quantity of high-contrast, photolithographic film strips similar to that taught in Nottorf, US. Pat. No. 3,142,568 comprising a gelatinous, silver bromochloride emulsion with a polyoxyethylene compound coated on polyethylene terephthalate film base were prepared for developer and sensitometry tests. The emulsion coatings were approximately 100.0 mgs. per square decimeter when dry.

Each strip was exposed for l025 seconds on a halftone sensitometer. The halftone sensitometer is comprised of a small vacuum frame so constructed that a 4 glass step wedge and a surfactants were prepared for developability tests using the aforementioned samples and controls.

A portion of said strips were processed in several standard lithographic developers and various compositions characteristic of this invention for 2 to 3 minutes. All test solutions were maintained at a pH of 10:] prior to processing between 65 and 75 F. Said standard developers essentially comprises aqueous hydroquinone solutions having conventional ingredients therein. Upon completion of development the films were immediately fixed in a conventional acid hardening and sodium thiosulfate fixing bath for about 2 minutes prior to rinsing. Processed samples were allowed to dry prior to sensitometric or speed and dot quality evaluations.

Speeds were determined on the basis of a conventional calculation system. The dots were evaluated upon microscopic observations of the characteristic halftone reproduction of 20 edge sharpness, dot size. opacity of small dots etc. and subjective ratings of the same on a numerical scale wherein.

L is excellent 2.0 is good 3.0 is acceptable 4.0 or more is unacceptable or poor.

This scale is used for all 50 percent dots (midtones) and I0 and 90 percent dots (shadow and highlights). Decimals are used to allow for estimates of intermediate quality.

The following compounds were used in the developers in the amounts listed in the tables below:

i. Pure trisodium ethylenediaminetetraacetate trihydrate.

2. Sodium lauryl sulfate 4 4. An isooctylphenwpolyethoxy ethanol of l2-l3 ethylene oxide groups.

5. The reaction product of technical oleyl alcohol with 20 moles of ethylene oxide.

5 6. The reaction product of tallow amine withSO moles of ethylene oxide.

Compounds 2. 3. 4. 5. and 6 are designated as compounds A. g

B, C. D, and E in the tables below.

General formulas of the standard and preferred developers 10 and sensitometric results were E XAMPLE XVlll Several samples of the high-contrast lithographic film bearing an exposed emulsion such as that described in examples l5 l-XVll were prepared. but the alkyl sulfate and polyethylene oxide compounds were removed from the emulsion. These films were prepared for sensitometric and developer tests with various modified. preferred solutions embodying this invention. The solutions comprised standard hydroquinone developers having a particular ionic. alkyl salt and polyethylene oxide compound added thereto. All processing operations and sensitometric determinations were repeated as described in examples l-XVll.

It was observed that. while all the developers yielded good or excellent midtones. standard developers. 1 and 3, similar to those of examples XI and XlV respectively produced acceptable shadow and highlight. but image color was poor. The preferred developers gave superior "dot quality," and sharper images were produced and speed was increased. Also there 3. The sodium salt of the sulfate of a mixture of oleyl and plied to those systems involving modified lithographic emulcetyl alcohols in which oleyl predominates.

sign to obtain superior results.

DEVELOPER COMPOSITIONS AND TEST RESULTS Developer and concentration in grams per liter Ingredients I II III IV V VI VII VIII XI X XI XII XIII XIV XV XVI XVII Hydroquinone 22.5 22.5 22.5 22.5 20 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Parai'ormaldehyde 7.5 7.5 7.5 7.5 Sequestrene NAaT 1.0 1 0 1 0 1.0 1.0 1.0 1.0 1.0 Glucono delta lactone Ethylene glycol 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 Boric acid. 7. 5 7. 6 7. 5 7. 5 Sodium hydroxide 4. 5 4. 5 4. 5 4. 5 4. 5 4. 5 4. 5 4. 5 Sodium formaldehyde bisulfite 42.5 42.5 42.5 42.5 42.6 42.5 42.5 42.5 42.5 72.5 74.5 72.5 72.5 Sodium metaborate (octahydrate) 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Sodium sulfite (anhydrous). 30.0 30.0 30.0 30.0 6.0 6.0 6.0 6. 0 2.0 2.0 2.0 2. 0 2.0 Sodium carbonate (anhydrous) 12.5 12.5 12.5 12.5 48.0 48.0 48.0 Sodium bromide 1 4 1.4 1 4 l 4 1. 1.75 1. 75 1. 75 Sodium bicarbonate. 4. 75 4.75 4.75 4.75 5 6 5 6 5 6 Sodium metabisulfite. 2 2 2.2 2 2 2.2

Potassium bromide. Potassium carbonate (anhydrous) 2 Compound A. 3 Compound B 4 Compound 0.- 5 Compound D. 6 Compound E. Relative speed Dot quality:

Midtones Shadow and highlights.

Dot ratings Amount added Rela- Shadow and Surfactants gram/ tive highlights Film sample Developer added Type liter speed Midtones (10% and Image color Litho sample 1 Excellent... Acceptable... Poor. Litho sample (no 2 Compound Anionic... 0.875 250 ...do Excellent Gooc.

surfactants). A.

OoCmpound Nonionic 0. 5 Litho Sample 3 100 Good Acceptable... Poor. Litho sample (no 4 Compound Anionic... 1.0 207 ...do Excellent... Good.

surfactants).

Nonionic 0. 5

Compound Additional film samples of the type referred to in example XVlll were prepared in the manner previously described for developability tests with several developers of the type disclosed in example Xi and various modifications thereof to illustrate the advantage of the cofunctioning surfactants over that practiced heretofore. In this instance the standard developer and the same containing only one of each type of the preferred surfactants was compared with a similar standard developer having a preferred combination. The developed samples were fixed in conventional acid-hardening solutions, washed and dried. Shortly thereafter sensitometry of the dried-processed films was determined and the results The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A lithographic silver halide developer solution comprising an aqueous developer solution containing hydroquinone or a substituted hydroquinone and the following ingredients:

Alkali metal alkyl sulfate 0.2-4 g.

Nonionic polyethylene oxide surfactant Water to make 1 L.

2. A developer solution according to claim 1, wherein the alkali metal alkyl sulfate is sodium dodecyl sulfate.

3. A developer solution according to claim I, wherein said surfactant is isooctylphenyl polyoxyethanol.

obtained therefrom recorded below. 5 4. A developer solution according to claim 1, wherein the Dot ratings Amount added Rela- Shadow and Surfactants gram/ tlve highlights Film sample Developer added Type liter speed Midtones (10% and 90%) Image color C(empound Nonionic 0.5 Excellent Acceptable... Unaccept. Compound Anionic..- 0.876 200 Unacceptnn. Unaeeept Good.

A. d 0.875 Compound car'lpound Nonionic 0.5 100 Excellent Excellent. Do. d XI 300 Do.

the surfactants are excluded from the system entirely, a combination of the two surfactants provided good speed, dot quality, and image color.

Unaccept- UnaccepL 

2. A developer solution according to claim 1, wherein the alkali metal alkyl sulfate is sodium dodecyl sulfate.
 3. A developer solution according to claim 1, wherein said surfactant is isooctylphenyl polyoxyethanol.
 4. A developer solution according to claim 1, wherein the alkali metal alkyl sulfate is sodium dodecyl sulfate, and said surfactant is isooctylphenyl polyoxyethanol.
 5. A developer solution according to claim 1, wherein the alkali metal alkyl sulfate is a mixture of sodium cetyl sulfate and sodium oleyl sulfate.
 6. A developer solution according to claim 1, wherein said surfactant is the monooleyl ether of polyethylene glycol containing about 20 oxyethylene groups.
 7. A developer solution according to claim 1 wherein the surfactant is the condensation product of tallow amine with at least 20 moles of ethylene oxide. 